Conventionally, a shield case has been employed in order to protect electronic parts such as chips mounted on a board from electromagnetic wave noise or dust etc. from the outside.
FIG. 6 shows a perspective outside view of a conventional MEMS microphone. FIG. 7(a) is a side view of the conventional MEMS microphone. FIG. 7(b) is a plan view of the conventional MEMS microphone. FIG. 7(c) is a longitudinal sectional diagram (a sectional diagram along a line A-A in FIG. 6) of the conventional MEMS microphone.
The conventional MEMS microphone 300 shown in FIGS. 6 and 7 is configured by a board 301, an MEMS chip 200 and a shield case 303. The MEMS chip 200 is a chip for converting a sound signal into an electric signal.
Such an MEMS microphone 300 is used in a state of being mounted on the main board of a mobile phone etc. In this case, in order to secure a passing path of the sound signal, the sound hole for the microphone of the casing in the mobile phone and a sound hole 303c on the top plate 303a of the shield case are disposed and mounted in an overlapped manner. However, even if the sound holes are disposed at an almost overlapping position, when there is a space between the casing and the shield case 303, the sound signal leaks from the space and so there arises a case that the acoustic characteristics designed in advance changes.
Thus, an improvement has been made that a gasket made of material such as rubber of silicon is adhered and sandwiched between the top plate 303a of the shield case and the casing of the mobile phone thereby to eliminate the space.
Further, similarly in a view point of the airtightness, a patent document 1 describes an example in which a gasket is pasted between a transparent panel plate and an external cover in the mechanism of the display portion of a mobile phone (see the patent document 1, for example).
Patent Document 1: JP-A-2005354377